In A Nutshell

There’s a group of rats that are working hard to get rid of their rather negative image, and they’re doing it by sniffing out land mines and tuberculosis. Giant African pouched rats are being trained to stop and point out the presence of certain smells—specifically, TNT and the bacteria that causes tuberculosis. They’re already making a huge impact in clearing land mines in countries like Tanzania and Angola and in diagnosing TB patients with a much higher success rate than the accepted two-thirds.

The Whole Bushel

Rats have been connected with the spread of disease for centuries, rightfully or wrongfully so. Today, though, if you see a man walking a rat on a leash through Tanzania, that’s not just any rat: Chances are that’s a highly trained, bomb-sniffing rat.

APOPO is an organization that trains giant rats like some other organizations train dogs. The Anti-Personnel Landmines Detection Product Development organization (the Dutch acronym is APOPO) got its start in 1997, with the work of a man named Bart Weetjens. Weetjens, who had always kept rats as pets, was also working on the problems facing a number of countries around the world—land mines and how to safely remove them.

The two came together in an incredible way. Giant African pouched rats are very, very intelligent and easy to train; Weetjens and his organizations developed a training program for the rats where they would be rewarded for stopping and indicating the presence of a certain smell. In the case of the rats trained to sniff out land mines, they’re trained to stop and sniff when they’re on top of a patch of ground that smells like TNT. They’re rewarded with a treat when they identify the right smells in training, and by the time they’re out in the field, it’s second nature. (They’re large rats, but they’re not heavy enough to set off the land mines.)

The organization calls them HeroRATS, and for good reason. Once fully trained, a rat can cover about 19 square meters (200 ft2) in about 20 minutes and will respond to any type of land mine. Places that the rats indicate are clearly marked, then the mines are later destroyed with explosives. The rats have already been responsible for clearing the mines from huge sections of land, and more and more are being trained.

The whole program was a massive success, and trainers decided to branch out a bit. Now, rats are also being trained to diagnose tuberculosis.

In many countries, tuberculosis is still a huge problem. There are about nine million cases reported each year, and there were around 1.5 million deaths in 2013. Identifying cases quickly means that treatment isn’t far behind, and rats are incredibly fast at what they do, able to process about 100 samples every 20 minutes.

The rats are trained in much the same way they’re trained to find land mines, but instead of TNT, the tuberculosis-detecting rats are looking for the scent of the bacteria that causes the disease, Mycobacterium tuberculosis. Researchers and trainers aren’t even entirely sure what the rats are looking for, what they’re smelling and how they’re so good at what they do, but they’re incredibly good. TB clinics that use the rats as a diagnostic tool have been able to increase their productivity by as much as 40 percent.

The traditional way of diagnosing TB is looking at samples through a microscope, but it’s a pretty hit-or-miss sort of system. Of the estimated nine million people who are infected with TB, as many as three million go undiagnosed or missed. Those that also have HIV present another problem, as the presence of the HIV virus makes tuberculosis even harder to detect under the microscope.

With the rats, though, there’s no one-third misdiagnosis.

There’s a whole host of benefits to using rats in both mine and tuberculosis detection. It’s much, much more affordable than the respective alternatives in the long run, and the average rat has a working lifespan of up to eight years. They’re readily available, easy to raise, and they’re extraordinarily good at what they do.